1. Field of the Invention
The present invention relates in general to a variable light transmittance device for controlling transmittance of light therethrough by means of liquid crystal, electrochromic (EC) material, or the like. More particularly, the present invention relates to a structure for connecting an electrical terminal to the device.
2. Description of the Prior Art
Hitherto, various devices have been proposed for controlling transmittance of light therethrough, such as the light valve, the liquid crystal display and the electrochromic display. These devices have been used to display drawings, letters or the like, or to control transmittance of the sunlight through a window pane or the like.
In order to clarify the task of the present invention, conventional structures for connecting a terminal to a variable light transmittance device will be outlined in the following.
Japanese Utility Model First Provisional Publication 1-77620 discloses a first device for controlling transmittance of light by means of liquid crystal. The first device comprises two oppositely arranged substrates. The inner surfaces of the substrates are coated with transparent and conductive films which are spaced from each other. Two units each consisting of the substrates and the films are slightly displaced in parallel relative to each other. With this, there is provided two exposed end portions of the units. A layer of liquid crystal is interposed between oppositely arranged major surfaces of the films. Each end portion has a through hole for fixing an electrical terminal thereon. A fixing portion of the terminal is passed through the through hole and fixed to the end portion. With this, the terminal is electrically connected to the film. A lead is connected to the terminal for applying voltages between films, thereby controlling transmittance of light through the first device.
Japanese Utility Model First Provisional Publication 1-73831 discloses a second device for controlling transmittance of light by means of liquid crystal. The second device also comprises two oppositely arranged substrates of which inner surfaces are coated with two oppositely arranged transparent and conductive films, and a liquid crystal layer which is interposed between the films. There is provided a notched end portion for providing a space defined above an end portion of each substrate, to which end portion silver paste is applied. A terminal is soldered to the silver paste which is electrically connected the film.
However, the above-mentioned conventional first and second devices have following drawbacks.
First, since it is necessary to displace the units of the first device relative to each other or to notch end portions of the second device for connecting the terminal to the first or the second device, an entire major surface of the first or second device can not serve for controlling transmittance of light therethrough.
Secondly, since a connecting process of the terminal to the first or the second device is relatively complicated, the production cost is increased.